High voltage circuit interrupter switch arrangement

ABSTRACT

A high voltage circuit interrupter is enclosed within an integrally formed insulating housing that includes the operating mechanism enclosure, the insulator portion, and the muffler portion. The integrally molded insulating housing increases the interrupting capability of the interrupter. Also provided at one end of the housing is an alumina particle muffler for absorbing hot arc gases produced when the switch opens or closes. A trailer is connected to the moving contacts of the switch and the trailer is formed of a material that produces an arc quenching gas when exposed to an electrical arc. A very small vent hole is provided through the housing adjacent the muffler to provide controlled venting to the atmosphere so that the gases are essentially confined within a suitably large volume of the housing to increase the dielectric strength. External and internal surface coatings may also be employed to provide voltage grading and to eliminate corona and RIV noise.

United States Patent 1 1 Harner et al.

1 51 Sept. 30, 1975 [751 Inventors: Robert H. Harrier, Park Ridge;

Thomas J. Tobin, Morton Grove,

both of 111 [73] Assignee: S and C Electric Company, Chicago,

[22] Filed: Oct. 11, 1973 21 App]. No.: 405,496

[52] US. Cl 200/144 C; 200/146 R; 200/149 A Primary E.\'ami 1erR0bert S. Macon Attorney, Agent, 0rFirmKirk1and & Ellis 1 1 ABSTRACT A high voltage circuit interrupter is enclosed within an integrally formed insulating housing that includes the operating mechanism enclosure, the insulator portion, and the muffler portion. The integrally molded insulating housing increases the interrupting capability of the interrupter. Also provided at one end of the housing is an alumina particle muffler for absorbing hot arc gases produced when the switch opens or closes. A trailer is connected to the moving contacts of the switch and the trailer is formed of a material that produces an arc quenching gas when exposed to an electrical arc. A very small vent hole is provided through the housing adjacent the muffler to provide controlled venting to the atmosphere so that the gases are essentially confined within a suitably large volume of the housing to increase the dielectric strength. External and internal surface coatings may also be employed to provide voltage grading and to eliminate corona and RI\/ noise.

18 Claims, 7 Drawing Figures US. Patent Sept. 30,1975 Sheet 1 of 3 3,909,570

/ [q k/trim! ///2 I HIM US. Patent Sept. 30,1975 Sheet 2 of3 3,909,570

U.S. Patent Sept. 30,1975 Sheet 3 of3 3,909,570

HIGH VOLTAGE CIRCUIT INTERRUPTER SWITCH ARRANGEMENT BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention generally relates to high voltage circuit interrupting switches and more particularly to trailer-liner load interrupters suitable for high voltage systems; for example, 15 KV and higher.

2. Description of the Prior Art 5 Various types of high voltage circuit interrupter switch arrangements have been developed to effect efficient interruption of current flow in high voltage cir cuits. One type of circuit interrupter switch is commonly known as a trailer-liner load interrupter which utilizes a contact trailer and arc chamber liner formed of a material that produces an arc quenching gas upon exposure to an electrical arc when the switch contacts are either opened or brought into proximity during closing. Such trailer-liner loadd interrupters are widely used at voltages up to KV and inn some applications up to 34.5 KVl However, at high voltages it has heretofore been considered necessary to have two or more sets of contacts operating simultaneously to produce two or more gaps in series to assure efficient current interruption. Circuit interrupters heretofore known to the art utilizing a single set of contacts for producing a single gap have not had sufficient voltage withstand capabilities for utilization at higher voltages.

Thus, it would be a highly desirable advance in the art to provide a high voltage circuit interrupter arrangement having a single set of contacts providing a single interrupting gap that may be utilized for a full range of interrupting duties including load currents, magnetizing current, line and cable dropping current, loop and parallel currents for use on high voltage systems; for example, 27 KV, 34 KV.

BRIEF SUMMARY OF THE INVENTION A high voltage circuit interrupter switch arrangement in accordance with the present invention comprises an integrally formed hollow switch insulating housing including a hollow operating mechanism enclosing portion, a hollow insulator portion and a hollow muffler portion formed as an integral unit so that the hollow interior portions of each communicate. Positioned within the insulator portion of the housing is a stationary contact means and a movable contact means for electrically engaging with the stationary contact means. Mounted on the movable contact means is a trailer means formed of a material that produces an arc quenching gas upon exposure to an electrical arc. Also positioned about the interior of the housing adjacent the contacts is a liner also formed of a material that produces an arc. quenching gas upon exposure to an electrical arc. An operating means is mounted Within the hollow interior portion of the operating mechanism enclosure portion of the housing. The operating means moves the movable contact means into and out of electrical engagement with the stationary contact means to make and break the electrical circuit between those members.

Use of an integrally molded insulating housing including the operating mechanism enclosing portion, the insulator portion, and the muffler portion, provides decided advantages over the prior art structure by substantially increasing the exterior dielectric voltage withstand capability of the interrupter arrangement over comparably sized conventional constructions. In addition, utilization of insulator skirts formed on the exterior of the insulator portion of the housing having varying diameters so that no two adjacent skirts are of the same diameter will also increase the wet voltage withstand capabilities of the interrupter arrangement.

The interrupter arrangement in accordance with the present invention also includes a muffler containing particles of inorganic material, preferably alumina ceramic inn the muffler portion of the housing which acts to effectively condense hot arc gases. In addition, use of two large volumes at either or both ends of the interrupting chamber permits retention of substantially all of the arc gas within the interrupter unit so that the arc gas density increases sufficiently and rapidly enough to improve the dielectric strength needed for effective current interruption. A controlled venting feature is also included so that the arc gases are effectively contained within the housing during interruption but are permitted to be slowly vented to the atmosphere after interruption.

An additional advantageous feature of the present invention is the utilization of a partially conductive coating over the inside of the operating mechanism housing to shield the internal mechanical components such'that corona and RIV noise are eliminated from these parts. A partially conductive coating may also be used over the outside of the arrangement to uniformly grade the voltage stress across the unit to increase the voltage withstand capability.

Additionally, internal stress shields may be molded into the insulating material to increase both the internal and external dielectric strengths of the unit. These internal electrical stress shields extend beyond the internal gap of the open contacts of the interrupter switch arrangements and improve the external as well as the internal dielectric strength of the unit thereby permitting a shorter interrupter unit to be constructed.

Accordingly, it is a primary object of the present invention to provide a high voltage circuit interrupter arrangernent in accordance with the present invention having an integrally molded insulating housing that includes the operating mechanism enclosing portion, insulator portion, and muffler portion to increase the external dielectric withstand voltage capabilities of the unit.

Another object of the present invention is to provide a high voltage circuit interrupter arrangement in accordance with the present invention including controlled venting for improving the dielectric strength of the unit throughout its cycle of operation.

Another object of the present invention is to provide a high voltage circuit interrupter arrangement utilizing v a muffler for effectively increasing the effective inter- I nal volume of the housing for collecting arc gases.

Another object of the present invention is to provide a high voltage circuit interrupter arrangement utilizing a partially conductive coating over the inside and outside of the insulating material of the housing to provide a uniform voltage grade distribution across the unit and Another object of the present invention is to provide a high voltage circuit interrupter switch arrangement having suitable internal volumes to retain arc gases within the unit to increase the dielectric strength of the interrupter switch arrangement during operation.

These and other objects, advantages, and features will hereinafter appear, and, for the purposes-of illustration, but not of limitation, exemplary embodiments of the present invention are illustrated in the accompanying drawings.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevational view of a preferred embodiment of the present invention.

FIG. 2 is a front partially fragmentary view of the embodiment illustrated in FIG. 1.

FIG. 3 is a cross-sectional view of a preferred embodiment of the present invention with the top cover of the operating mechanism enclosure removed.

FIG. 4 is a top view of the preferred embodiment illustrated in FIG. 3.

FIG. 5 is a cross-sectional view of the preferred embodiment illustrated in FIG. 3 showing the arcing contacts in an open position.

FIG. 6 is a cross-sectional view taken substantially along line 66 in FIG. 3.

FIG. 7 is a cross-sectional view taken substantially along line 7 in FIG. 3.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS With reference to FIG. 1, interrupter switch arrangement 10 comprises housing 12 molded of insulating material, such as epoxy resin, and preferably cycloaliphatic epoxy resin. Housing 12 includes operation mechanism enclosing portion 14, insulator portion 16, and muffler portion 18. Also integrally molded to the insulator and muffler portion of the housing is mounting flange 20. Attached to the upper end of operating mechanism enclosing portion 14 of housing 12 is cover 22 which sealably engages operating mechanism enclosing portion 12. Sealably engaging the bottom end of muffler portion 18 is breather cap 24, and mounted beneath breather cap 24 is rain cap. 26. A trigger arm 28 is mounted to shaft 30 by pin 32 (see FIG. 2). Electrical terminal bolts 34 extend through operating mechanism enclosing portion 14 and are retained by nuts 36 (see FIG. 3).

Insulator portion 16 of molded housing l2 comprises skirts 38 and 40 of varying diameters such that skirt 38 is of a larger diameter than skirt 40. The varying diameters of skirts 38 and 40 increase the wet voltage withstand capability of the insulator portion by preventing the dripping of rain water from contiguous skirts.

Flange has opening 42 (shown in dotted lines) through which a bolt or other suitable fastening means may be inserted to mount the interrupter switch arrangement 10.

With reference to FIG. 3, moving contact assembly 50 comprises contact rod 52 and bifurcated contact Stationary contact assembly 60 comprises stationary annular contact head 62 and annular sleeve 64 which is mounted by threads 66 into the base of contact adaptor 68. Contact adaptor 68 extends from its connection with stationary contact assembly 60 to the end of mounting flange 20 (see FIG. 7) to provide an electrical connection from stationary contact assembly 60 to the surface upon which the interrupter switch arrangement is mounted. Typically, an interrupter switch ar-. rangement would be mounted to a conducting metal frame which in turn is connected to an electrical current carrying conductor.

Mounted within the hollow internal area of insulator portion 16 is cylindrical liner 70 formed of a material that produces an arc quenching gas upon exposure to an electrical arc. i a

Contact rod 52 is connected at its upper end to arm 82 of operating mechanism 80. Operating mechanism comprises arms 82, 84, and 86 and spring 88. Ann 86 is mounted toshaft 30 by pin (see FIG. 4). Shaft 30 is electrically connected to electrical terminal bolts 34 so that an electrical circuit extends from terminal bolts 34, through arms 82 and 86, contact rod 52 to contact head 54. Operating mechanism 80 is of conventional design and is of the type generally illustrated in US. Pat. No. 2,662,139 Lindell et al., assigned to the same assignee as the present invention. However, any suitable means of moving the movable contactassembly out of and into engagement with the stationary contact assembly may be employed. In the case of operating mechanism 80, rotation of trigger arm 28 causes shaft 30 to rotate which in turn causes arms 82, 84 and 86 to cooperate to move moving contact assembly 50 into and out of engagement with stationary contact assembly 60. FIG. 5 illustrates the position of moving contact assembly 50 and arms 82,84 and 86 when moving contact assembly 50 is in an open position.

Positioned within muffler portion 18 of molded housing 12 is perforated sleeve 100. Perforated sleeve has a multiplicity of openings 102 therethrough to permit the exist of arc gases. Positioned around perforated sleeve 100 within muffler portion 18 are alumina particles 104 which act to absorb and cool hot arc gases produced when contact head 54 and annular contact head 62 disengage during switch opening or when a prestrike arc is formed as the contacts close. Positioned at the lower end of muffler portion 18 of housing 12 is exhuast nozzle assembly 106 having formed therein an exhaust channel 108. A perforated baffle l10prevents the alumina particles from clogging exhaust channel 108. Breather cap 24 is mounted over exhaust nozzle assembly 106 and holds exhaust nozzle assembly 106 in position. Breather cap 24 has openings 1 12 through the wall thereof to permit the gases exhausted through exhaust channel 108 to reach the ambient atmosphere.

Operation of the embodiment illustrated in FIGsf l, 2, 3, 4, 5, 6, and 7 is substantially as follows. Assume that the terminals of a high voltage electrical circuit connect to terminal bolts 34 and flange 20, resulting in current through terminal bolts 34, arms 82 and 86,

contact rod 52, contact heads 54 and 62, and contact I adaptor 68. Pivoting of trigger arm 28 causes shaft 30 to rotate which in turn causes arms 82, 84 and 86 to cooperate to move moving contact assembly 50 in a substantially upwardly linear direction. As contact arms 56 bifurcated contact head 54 disengage annular contact head 62 of stationary contact assembly 60 an electrical arc tends to form between the separating contact heads. However, when the are forms, both cylindrical liner 70 and trailer 58 produce an arc quenching gas which tends to inhibit and suppress the continued existence of the arc. As moving contact assembly 50 continues to move upwardly, the gases produced by liner 70 and trailer 58 tend to flow away from the arcing area towards the interior volume of muffler portion 18 and operating mechanism enclosing portion 14 of molded housing 12. Since the operating mechanism enclosing portion 14 is normally sealed by cover 22, the gases are retained within the housing thus raising the internal pressure within the interrupter switch arrangement thereby increasing the dielectric strength of the unit. Further, the arc gases tend to flow through the openings 102 in perforated sleeve 100 and are contacted by alumina particles 104. The alumina particles 104 tend to absorb and cool the hot arc gases thereby substantially increasing the ability of the interrupter switch arrangement 10 to hold the arc gases produced by the arcing. The gases produced by liner 70 and trailer 58 tend to extinguish the arc and prevent the are from stretching the entire distance of travel of moving contact assembly 50 thereby effectively interrupting the current flow between moving contact assembly 50 and stationary contact assembly 60. Exhaust channel 108 permits the exhaust gases cooled by alumina particles 104 to be slowly releasedfrom the housing 12 at a controlled rate thereby maintaining the internal dielectric strength caused by increased gas pressure. The internal pressure within the unit decreases gradually after the current has been interrupted, maintaining improved dielectric strength of the unit for some time after the interruption.

A semi-conductive coating may be utilized over the interior of the unit to relieve the electric field from the internal mechanism components of the interrupter switch arrangement 10, thus suppressing corona and RIV noise. Also, a semi-conductive coating may be provided over the exterior surfaces to provide a uniform voltage gradient overriding the leakage current and non-uniform voltage gradient due to non-uniform rain water and conductive contaminants on the surface of the interrupter switch arrangement 10. This effect leads to higher contaminated or wet dielectric strength of the unit.

Further, the utilization of an integrally formed housing 10 comprising the operating mechanism enclosing portion 14, the insulator portion 16, muffler portion 18, mounting flange substantially increases and will approximately double both the wet and dry withstand capabilities of the interrupter switch arrangement over conventionally constructed units of the same nominal size. The housing 10 may be formed entirely of an insulating material, or may be formed of metal components encapsulated in an insulating material. The use of filled cycloaliphatic epoxy is recommended for the insulating material because of its excellent mechanical insulating, arc resistant,and anti-tracking properties but any suitable material may be used.

In addition, FIGS. 3 and 5 show a lower internal stress shield 200 and upper stress shield 206 molded into housing 12. Internal stress shield 200 is an extended portion of contact adapter 68 that extends above annular contact head 62. Upper stress shield 206 is molded into the upper end of insulator portion 16 of housing 10. Upper stress shield 206 comprises annular body portion 208 and annular flange portion 210 extending downwardly below the position of bifurcated contact head 54 when in its fully raised position. (See FIG. 5.)

The internal stress shields 200 and 206 molded into insulating material increases both the internal and external dielectric strength of the unit. The internal stress shields 200 and 206 extend beyond the external contacts of the arrangement 10, i.e., flange 20 and terminal bolts 34, and therebyincrease the external dielectric strength of the unit. The internal stress shields 200 and 206 also improve vthe internal I dielectric strength of the internal gap of the interrupter switch arrangement by extending beyond the spaced gap be tween contact head 54 and annular contact head 62 when in a separated open position (see FIG. 5).

Thus, the internal stress shields 200 and 206 reduce the electrical stress on the outside of the unit by concentrating the stress inside the insulating material which can sustain high electrical stress. Thus, a more uniform lower stress is experienced near the operating mechanism and mounting bracket portions of the interrupter switch arrangement.

The internal dielectric strength of the arrangement is effected in the same manner as the external dielectric strength. Since the stress is concentrated inside the insulating material, lower more uniform stress is experienced at the internal gap. The stress would normally be concentrated at the ends of annular contact head 62 and bifurcated contact head 52. However, once the contact head 52 is within the upper stress shield 206, the internal electrical stress is determined predominantly by the upper and lower stress shields. Thus, essentially full gap dielectric strength is achieved at the internal gap which is greater than the dielectric strength of the full gap without the stress shields.

There is a maximum shield length which can be used as elongation in the shields beyond an optimum length will reduce the dielectric strength of the unit. However, longer insulating portions 16 of housing 10 would require different lengths of stress shields for optimum performance. It should be specifically noted that the internal stress shields of the present invention are not limited to an integrally formed insulating mechanism housing. The effect of these shields is even more dramatic when the mechanism housing and mounting bracket are of conventional metallic design.

It should be expressly understood that various changes modifications, and alterations in the structure of the present invention may be made without departing from the spirit and scope of the present invention as defined in the appended claims.

We claim:

1. A high voltage circuit interrupter arrangement for interrupting current flow between two electrical circuits comprising:

an integrally formed hollow unitary housing formed of an insulating material including:

an operating mechanism enclosing portion having a hollow interior;

an insulator portion having a hollow interior;

a muffler portion having a hollow interior, said hollow interiors of said operating mechanism enclosing portion, said insulator portion and said muffler portion communicating with one another;

stationary contact means mounted within the hollow interior of said insulator portion and electrically connected to one of the electrical circuits;

movable contact means electrically connected to another one of the electrical circuits and mounted for movement within said hollow interiors of said operating mechanism enclosing portion, said insulator portion, and said muffler portion; said movable contact means including a trailer means formed of a material that produces an arc quenching gas upon exposure to an electrical arc;

a cylindrical liner means positioned around the interior of the insulator portion, said liner means formed of a material that produces an arc quenching gas upon exposure to an electrical arc;

operating means mounted within the hollow interior of said operating'mechanism enclosing portion for moving the movable contact means into electrical engagement with the stationary contact means to connect the two electrical circuits and todisconnect out of electrical engagement to a spaced gap position to interrupt current flow between the two electrical circuits.

2. A circuit interrupter arrangement as claimed in claim 1, further comprising:

muffler means mounted within the hollow interior of said muffler portion for absorbing the gas produced by said trailer means and said liner means when an arc is formed upon engagement and disengagement of the movable contact means and the stationary contact means.

3. A circuit interrupter arrangement, as claimed in claim 2, wherein said muffler means comprises:

alumina particles;

a perforated sleeve mounted within the hollow interior of the muffler portion, said alumina particles confined between the sleeve and the interior of said muffler portion; and I said muffler portion has a small restricted opening there through communicating with the outside ambient air for controllably releasing the gases produced by the trailer means.

4. A circuit interrupter arrangement, as claimed in claim 1, wherein said insulator portion has annular skirts formed on the exterior thereof to increase the voltage withstand capabilities of the insulator portion.

5. A circuit interrupter arrangement, as claimed in claim 4, wherein said annular skirts are of varying diameters so that no two adjacent skirts are of the same diameter.

6. A circuit interrupter arrangement, as claimed in claim 1, wherein said muffler portion has a small restr'icted opening therethrough communicating with the outside ambient air for controllably releasing the gases produced by the trailer means.

7. A circuit interrupter arrangement, as claimed in claim 1, wherein said stationary contact means comprises:

an annular contact member having a hollow opening therethrough; and

said movable contact means comprises:

a bifurcated contact head having spreadable legs dimensioned to mate with the hollow opening in the annular contact member. t

8. A circuit interrupter arrangement, as claimed in claim 1, further comprising internal electrical stress shield means positioned within the insulating material of said integrally formed hollow housing and extending beyond the spaced gap between the movable contact means and the stationary contact means for increasing the dielectric strength of the switch arrangement by concentrating'the dielectric stress within the insulating material of said housing.

9. A circuit interrupter arrangement, as claimed in claim 1, further comprising:

semi-conductive coating means on the hollow interior of said housing for shielding the contents of said housing from electrical stress thereby reducing corona and RIV noise.

10. A circuit interrupter arrangement, as claimed in claim 1,'- 'further comprising semi-conductive coating means on the exterior of said housing for providing a uniformly graded voltage distribution across the arrangement thereby overriding leakage current and nonuniform voltage gradients due to conductive rain water and contaminants on the exterior of said housing.

11. A circuit interrupter arrangement, as claimed in claim 1, wherein said integrally formed hollow housing is made of cycloaliphatic epoxy resin.

12. A high voltage circuit interrupter arrangement comprising:

an integrally formed hollow unitary housing formed of an insulating material including: i

an operating mechanism enclosing portion having a hollow interior;

an insulator portion having a holIow interior;

a muffler portion having a hollow interior, said hollow interiors of said operating mechanism enclosing portion, said insulator portion and said muffler portion communicating withone another;

separable electrical contact means positioned within said housing for separating to interrupt current flow through the interrupter arrangement by sepa- V ration to a spaced gap;

internal electrical stress shield means positioned within the insulating material of said integrally formed hollow housing and extending beyond the spaced gap for increasing the dielectric strength of .the interrupter arrangement by concentrating the dielectric stress within the insulating material of said. housing. v l

.13. .A high voltage circuit interrupter arrangement comprising:

an integrally formed hollow unitary housing formed of an insulating material including:

an operating mechanism enclosing portion housing a hollow interiory,

an insulator portion having a hollow interior; I

, a muffler portion having a hollow interior said hollow interiors of said operating mechanism enclosing portion, said insulator portion and said muffler portion communicating with one another;

separable electrical contact means for separating to interrupt current flow, through the interrupter arrangement by separation to a spaced gap; and g a coating of a semi-conductive means on the hollow interior of said housing for shielding the interior of said housing thereby reducing corona and RIV noise. y

14. A high voltage circuit interrupter arrangement comprising:

an integrally formed hollow unitary housing formed of an insulating material including. 1

an operating mechanism enclosing portion having a hollow interior;

an insulator portion having a hollow interior;

a muffler portion having a hollow interior, said hollow interiors of said operating mechanism enclosing portion, said insulator portion and said muffler portion communicating with one another;

separable electrical contact means for separating to interrupt current flow through the interrupter arrangement by separating to a spaced gap; and

semi-conductive coating means on the exterior of said housing for providing a uniformly graded voltage distribution across the arrangement thereby overriding leakage currents and non-uniform voltage gradients due to conductive rain water and contaminants on the exterior of said housing.

15. A high voltage circuit interrupter arrangement comprising:

an integrally formed uitary housing formed of an insulating material including:

an operating mechanism enclosing portion having a hollow interior;

an insulator portion having a hollow interior, said hollow interiors of said operating mechanism enclosing portion, and said insulator portion communicating with one another;

separable electrical contact means for separating to interrupt current flow through the interrupter arrangement by separating to create a spaced gap;

a muffler portion having a hollow interior communicating with the hollow interiors of said operating mechanism enclosing portion and said insulator portion, and said muffler portion having a small restricted opening therethrough communicating with the outside ambient air for controllably releasing arc gases produced when current flow is interrupted.

16. A high voltage circuit interrupter arrangement comprising:

an operating mechanism enclosure having a hollow interior;

an insulator formed of an insulating material having a hollow interior connected at one end to said operating mechanism enclosure, said hollow interiors of said operating mechanism enclosure and said insulator communicating with one another;

first and second separable electrical contacts positioned within the hollow interior of said insulator,

said first and second contacts being separable to create a spaced gap between the first and second contacts when separated to interrupt current flow through the interrupter arrangement;

first and second internal electrical stress shields positioned around said first and second contacts respectively and within the insulating material of said insulator, said first and second stress shields extending closer to one another than the spaced gap between the separated first and second contacts so that the dielectric strength of the interrupter arrangement is increased by concentrating the dielectric stress within the insulating material of said insulator when the first and second contacts are separated.

17. A high voltage circuit interrupter arrangement comprising:

an integrally formed hollow unitary housing formed of an insulating material including:

an insulator portion having a hollow interior;

a muffler portion having a hollow interior connected to one end of said insulator portion;

a hollow gas receiving portion forming a enclosed gas receiving volume mounted at the second end of said insulator portion, said gas receiving volume of said gas receiving portion, the said hollow interior of said insulator portion and said hollow interior of said muffler portion communicating with one another;

stationary contact means mounted within the hollow interior of said insulator portion;

movable contact means mounted for movement within said hollow interiors of said gas receiving portion, said insulator portion, and said muffler portion; said movable contact means including a trailer means formed of a material that produces an arc quenching gas upon exposure to an electrical arc;

a cylindrical liner means positioned around the interior of the insulator portion, said liner means formed of a material that produces an arc quenching gas upon exposure to an electrical arc.

18. A circuit interrupter arrangement, as claimed in claim 17, wherein the integrally formed hollow unitary housing is made of cast filled cycloaliphatic epoxy resin. 

1. A high voltage circuit interrupter arrangement for interrupting current flow between two electrical circuits comprising: an integrally formed hollow unitary housing formed of an insulating material including: an operating mechanism enclosing portion having a hollow interior; an insulator portion having a hollow interior; a muffler portion having a hollow interior, said hollow interiors of said operating mechanism enclosing portion, said insulator portion and said muffler portion communicating with one another; stationary contact means mounted within the hollow interior of said insulator portion and electrically connected to one of the electrical circuits; movable contact means electrically connected to another one of the electrical circuits and mounted for movement within said hollow interiors of said operating mechanism enclosing portion, said insulator portion, and said muffler portion; said movable contact means including a trailer means formed of a material that produces an arc quenching gas upon exposure to an electrical arc; a cylindrical liner means positioned around the interior of the insulator portion, said liner means formed of a material that produces an arc quenching gas upon exposure to an electrical arc; operating means mounted within the hollow interior of said operating mechanism enclosing portion for moving the movable contact means into electrical engagement with the stationary contact means to connect the two electrical circuits and to disconnect out of electrical engagement to a spaced gap position to interrupt current flow between the two electrical circuits.
 2. A circuit interrupter arrangement as claimed in claim 1, further comprising: muffler means mounted within the hollow interior of said muffler portion for absorbing the gas produced by said trailer means and said liner means when an arc is formed upon engagement and disengagement of the movable contact means and the stationary contact means.
 3. A circuit interrupter arrangement, as claimed in claim 2, wherein said muffler means comprises: alumina particles; a perforated sleeve mounted within the hollow interior of the muffler portion, said alumina particles confined between the sleeve and the interior of said muffler portion; and said muffler portion has a small restricted opening there through communicating with the outside ambient air for controllably releasing the gases produced by the trailer means.
 4. A circuit interrupter arrangement, as claimed in claim 1, wherein said insulator portion has annular skirts formed on the exterior thereof to increase the voltage withstand capabilities of the insulator portion.
 5. A circuit interrupter arrangement, as claimed in claim 4, whErein said annular skirts are of varying diameters so that no two adjacent skirts are of the same diameter.
 6. A circuit interrupter arrangement, as claimed in claim 1, wherein said muffler portion has a small restricted opening therethrough communicating with the outside ambient air for controllably releasing the gases produced by the trailer means.
 7. A circuit interrupter arrangement, as claimed in claim 1, wherein said stationary contact means comprises: an annular contact member having a hollow opening therethrough; and said movable contact means comprises: a bifurcated contact head having spreadable legs dimensioned to mate with the hollow opening in the annular contact member.
 8. A circuit interrupter arrangement, as claimed in claim 1, further comprising internal electrical stress shield means positioned within the insulating material of said integrally formed hollow housing and extending beyond the spaced gap between the movable contact means and the stationary contact means for increasing the dielectric strength of the switch arrangement by concentrating the dielectric stress within the insulating material of said housing.
 9. A circuit interrupter arrangement, as claimed in claim 1, further comprising: semi-conductive coating means on the hollow interior of said housing for shielding the contents of said housing from electrical stress thereby reducing corona and RIV noise.
 10. A circuit interrupter arrangement, as claimed in claim 1, further comprising semi-conductive coating means on the exterior of said housing for providing a uniformly graded voltage distribution across the arrangement thereby overriding leakage current and non-uniform voltage gradients due to conductive rain water and contaminants on the exterior of said housing.
 11. A circuit interrupter arrangement, as claimed in claim 1, wherein said integrally formed hollow housing is made of cycloaliphatic epoxy resin.
 12. A high voltage circuit interrupter arrangement comprising: an integrally formed hollow unitary housing formed of an insulating material including: an operating mechanism enclosing portion having a hollow interior; an insulator portion having a hollow interior; a muffler portion having a hollow interior, said hollow interiors of said operating mechanism enclosing portion, said insulator portion and said muffler portion communicating with one another; separable electrical contact means positioned within said housing for separating to interrupt current flow through the interrupter arrangement by separation to a spaced gap; internal electrical stress shield means positioned within the insulating material of said integrally formed hollow housing and extending beyond the spaced gap for increasing the dielectric strength of the interrupter arrangement by concentrating the dielectric stress within the insulating material of said housing.
 13. A high voltage circuit interrupter arrangement comprising: an integrally formed hollow unitary housing formed of an insulating material including: an operating mechanism enclosing portion housing a hollow interior; an insulator portion having a hollow interior; a muffler portion having a hollow interior, said hollow interiors of said operating mechanism enclosing portion, said insulator portion and said muffler portion communicating with one another; separable electrical contact means for separating to interrupt current flow through the interrupter arrangement by separation to a spaced gap; and a coating of a semi-conductive means on the hollow interior of said housing for shielding the interior of said housing thereby reducing corona and RIV noise.
 14. A high voltage circuit interrupter arrangement comprising: an integrally formed hollow unitary housing formed of an insulating material including: an operating mechanism enclosing portion having a hollow interior; an insulator portion having a hollow interior; a mufFler portion having a hollow interior, said hollow interiors of said operating mechanism enclosing portion, said insulator portion and said muffler portion communicating with one another; separable electrical contact means for separating to interrupt current flow through the interrupter arrangement by separating to a spaced gap; and semi-conductive coating means on the exterior of said housing for providing a uniformly graded voltage distribution across the arrangement thereby overriding leakage currents and non-uniform voltage gradients due to conductive rain water and contaminants on the exterior of said housing.
 15. A high voltage circuit interrupter arrangement comprising: an integrally formed uitary housing formed of an insulating material including: an operating mechanism enclosing portion having a hollow interior; an insulator portion having a hollow interior, said hollow interiors of said operating mechanism enclosing portion, and said insulator portion communicating with one another; separable electrical contact means for separating to interrupt current flow through the interrupter arrangement by separating to create a spaced gap; a muffler portion having a hollow interior communicating with the hollow interiors of said operating mechanism enclosing portion and said insulator portion, and said muffler portion having a small restricted opening therethrough communicating with the outside ambient air for controllably releasing arc gases produced when current flow is interrupted.
 16. A high voltage circuit interrupter arrangement comprising: an operating mechanism enclosure having a hollow interior; an insulator formed of an insulating material having a hollow interior connected at one end to said operating mechanism enclosure, said hollow interiors of said operating mechanism enclosure and said insulator communicating with one another; first and second separable electrical contacts positioned within the hollow interior of said insulator, said first and second contacts being separable to create a spaced gap between the first and second contacts when separated to interrupt current flow through the interrupter arrangement; first and second internal electrical stress shields positioned around said first and second contacts respectively and within the insulating material of said insulator, said first and second stress shields extending closer to one another than the spaced gap between the separated first and second contacts so that the dielectric strength of the interrupter arrangement is increased by concentrating the dielectric stress within the insulating material of said insulator when the first and second contacts are separated.
 17. A high voltage circuit interrupter arrangement comprising: an integrally formed hollow unitary housing formed of an insulating material including: an insulator portion having a hollow interior; a muffler portion having a hollow interior connected to one end of said insulator portion; a hollow gas receiving portion forming a enclosed gas receiving volume mounted at the second end of said insulator portion, said gas receiving volume of said gas receiving portion, the said hollow interior of said insulator portion and said hollow interior of said muffler portion communicating with one another; stationary contact means mounted within the hollow interior of said insulator portion; movable contact means mounted for movement within said hollow interiors of said gas receiving portion, said insulator portion, and said muffler portion; said movable contact means including a trailer means formed of a material that produces an arc quenching gas upon exposure to an electrical arc; a cylindrical liner means positioned around the interior of the insulator portion, said liner means formed of a material that produces an arc quenching gas upon exposure to an electrical arc.
 18. A circuit interrupter arrangement, as claimed in claim 17, wherein the integrally formed hollow unitary housing is made of cast filled cycloaliphatic epoxy resin. 